Teachable, a.
Capable of being taught; apt to learn; also, willing to receive instruction; docile. We ought to bring our minds free, unbiased, and teachable, to learn our religion from the Word of God. I. Watts.
Shades of meaning
Fernald has no entry of its own for teachable; he lists it under docile.
He lists it without comment; the entries above explain its neighbors.